The product is an Instafence (also called Instant Fence or wireless
fence). The manual for the thing is available on petsafe.com, look for
the PIF-300 product (which also includes the collar). It transmits a
short range signal at 18.7 kilohertz using large air coils as
antennas. It is designed to contain a dog within a 90 foot radius and
to issue mild shocks if/when the pet attempts to leave the area. It
does not work with a buried wire loop, it uses the transmitter to
define the dogs play area.
For anyone interested in purchasing one, they are horribly expensive
(list price $280) and they have a special battery for the collar,
which is only used by petsafe, available at 6 dollars each. The
batteries don't last long. The range is only 90 feet, so it doesn't
allow the pet to move very much.
It appears to be grossly over-engineered as well, an ASIC feeds one
each amplifier separately and the amps appear to run at very low
power. No doubt a much cheaper transmitter could be made, this one is
also physically large as well!
For anyone interested in the petsafe IF100 vlf transmitter, you can
look on www.petsafe.net
for the manufacturers info-
Or, check out pictures, schematic and field strength documentation at:
Here are some notes based on my personal observations (before I
returned the device).
SW2 is hardwired, and is not adjustable as shown in the schematic. For
some reason, this switch was called 'mode' back in 1998 when petsafe
submitted the documentation to the FCC. The schematic shows it as a
switch though. When looking at the schematic, the position of the
switch in the schematic is shown correctly.
Switching S3 to ground selects low power transmit.
The pot, R33 is the power control.
The ASIC is marked as follows:
It is impossible to tell how many turns are on each loop (transmit
antenna). But, each of the 4 loops has the same size wire and has a dc
resistance of 4.5 ohms.
Vdd for the ASIC is 4.85 volts.
I have spectral output for each of the output lines (X, Y, Z). The
spectral display shows the same signal on each output although the
same output signal on all 3 output lines, although there are different
peak amplitudes (some of the amp stages are driven harder than others,
but all have the same basic input signals).
There are 3 audio amp chips, they are each the LM 1875T. They can run
20 watts output, but the output power is much lower than 20 watts for
each stage. This is based on the V+ being very low (16.8v) and the
observation that the 1.8A wall wart (at 14v ac) runs very cool. Also,
although the heat sinks for each stage are very small, they are barely
warm to the touch.
If anyone wants to see the spectral output of the ASIC that feeds the
amps, send me an emmail to:
K Y 1 K at pivot dott nett.